Independent Synthesis and Structural Characterization of a Mononuclear Copper−Hydroxide Complex Previously Assigned as a Copper−Superoxide Species

A compound previously reported (Harata et al. J. Am. Chem. Soc. 1994, 116, 10817) as the first structurally characterized example of a monocopper−superoxo complex is shown instead to be [(tppa)Cu(OH)]ClO4, a novel mononuclear hydroxide complex of copper stabilized by intramolecular hydrogen-bonding interactions. An X-ray crystal structure of the compound independently prepared from tppa, Cu(ClO4)2·6H2O, and aqueous NaOH is identical to that mistakenly attributed to the superoxo complex.